1. Field of the Invention:
This invention relates to a punch assembly for applying snap fasteners, buttons, ornamental marks, or the like to workpieces such as garment fabrics.
2. Description of the Prior Art:
Punch assemblies of this character are known for joining together a pair of fastening elements by driving one such element through a workpiece into the other element. A typical example of such punch assembly is disclosed in Japanese Utility Model Laid-Open Publication No. 62-83830 Issued May 28, 1987, corresponding to U.S. Pat. No. 4,736,880 which assembly comprises a clamp holder, a pair of clamps pivotally mounted thereon for releasably holding one of the fastener elements, a punch holder slidably received in the clamp holder and connected at one end to a reciprocable ram and at the other end to a punch. The clamp holder is divided into identical halves which are normally urged toward each other; i.e. against the punch holder by a pair of spring members whose tension is controlled so as to impose a predetermined amount of braking or damping force upon the clamp holder relative to the punch holder whereby the danger of impairing the workpiece under excessive impinging stress is eliminated.
However, the prior punch assembly has a drawback in that the divided halves of the clamp holder are prone to shift out of position relative to each other after prolonged use, allowing the fastening element to fall off or making it otherwise difficult to hold the same in the proper position registering with the mating element underlying the workpiece.